For providing an electrical connection between offshore facilities such as an array of wind turbines in a wind park or an oil rig or between an offshore facility and an onshore power plant sea cables are used. A sea cable is usually guided vertically from a pillar of a first offshore facility to an essentially horizontal course on the sea bed or below the sea bed and is then guided vertically to a pillar of a second offshore facility. According to their specific structure and materials, sea cables can tolerate being bent up to a specific minimal bending radius. A more severe bending could result in a damage of an electrical cable assembled in the sea cable. Thus, a sea cable is usually guided by means of a J-shaped tubing arrangement restricting the bending of the sea cable at the critical point of transition from vertical to horizontal. Erosion of the seabed around the lower end of the J-tube caused by tide, currents or waves can lead to a varying distance between a fixing point of the cable assembly at an offshore facility and a point where a suspended cable assembly reaches the seabed. Due to this fact, curvature limiters comprising a variable curvature are applied for compensating geometrical alterations of the course of the sea cable caused by varying ground levels.
A curvature limiter comprising a variable curvature is disclosed in EP 1 616 377 B1. A sea cable being guided from vertical to horizontal is secured against excessive bending by means of an arrangement comprising several pipe segments which can be pivoted relative to one another so far that the bending of a cable inserted into the pipe segments does not fall below the minimum bending radius of the cable.
A second type of curvature limiter comprising a variable curvature is disclosed in EP 2 158 654 B1. It comprises a first, J-shaped tube guiding a sea cable from a vertical to a horizontal direction, a second, rigid tube and a third, flexible tube both extending in an essentially horizontal direction on or below the seabed. The first and the second tube are connected by means of a hinged element which allows both tubes to pivot relative to one another. This mechanism allows a sea cable mounted to an offshore facility and inserted in the tubing arrangement being guided to a horizontal course on or below the seabed without being exposed to an excessive bending radius.
The curvature limiters disclosed in EP 1 616 377 B1 and in EP 2 158 654 B1 provide a reliable protection of a sea cable arranged within them. However, due to a variety of different components, the process of assemblage is complex. Further, the process of installing a sea cable within these types of curvature limiters is difficult and dangerous because it requires the use of divers and/or remotely operated vehicles.